Protein is one of the three major components of all foods (fats, carbohydrates, protein)
and is required for cell repair of the microscopic trauma that is associated with exercise
and training. It is NOT a particularly good energy source, but is available
for that purpose in malnourished individuals.

We measure a persons nitrogen balance to assess protein metabolism. A negative nitrogen
balance indicates that protein requirements are not being met by our diet and protein
is being scavenged from healthy tissue to maintain essential body functions. A negative
nitrogen balance will impair training gains in muscle mass and strength.

Protein molecules are built from amino acids. The protein in our diet is broken down in the small
intestine into its component amino acids which are absorbed through
the intestinal lining cells and then transported to cells throughout the body
where they are then available to rebuild and repair cellular proteins. There is
no protein storage capacity beyond the protein that is an integral part of cells
throughout the body. This means cell repair requires either amino acids
from protein eaten that day or from amino acids scavenged from cell protein breakdown
elsewhere in the body. Any excess dietary protein - beyond that needed for cell repair -
is converted into carbohydrates (gluconeogenesis) or fat.

HOW MUCH PROTEIN DO YOU REALLY NEED?

This article summarizes
the change in the answer to that question over time.

Several recent articles support a number of
1.2 grams of protein per kg of body weight per day
for the average individual (omnivore as well as vegan).
(article 1,
article 2).

A third study from a team of researchers at Kent State
University and McMaster University evaluated a group of 12
physically active male subjects over two months of resistance training. They
found a protein intake of 81 grams per
day (1.0 g per kg of body-weight for a 180 lb male) left the athletes
in negative nitrogen balance (indicating this level was inadequate).

Taken together, these support a number of 1.2 grams of protein per kg body
weight per day for an active individual. For a 70 kg
man (156 pounds) that translates into 84 grams of protein
a day.

Those on a regular resistance training program or endurance athletes
requiring more than the average individual in training induced micro trauma repair may
have a higher requirement. To quote:
"Research has indicated that increased dietary protein intake (up to 1.6 g
protein per kg per day) may enhance the hypertrophic response to resistance
exercise."

Based on these papers I think the following are reasonable recommendations for
daily protein intake:

Strength - 1.6-1.7 grams of dietary protein per kg of body-weight per day

Endurance - 1.2-1.4 grams of dietary protein per kg of body-weight per day

Average person exercising for 30 minutes 4x a week - 1.0 - 1.2 grams
of dietary protein per kg of body-weight per day

The average 70 kg (154 pound) recreational cyclist will need from 80 to 100 grams of
protein per day. And for those at the elite level, the requirement may be
as high as 120 grams. As active athletes
consume more Calories a day than a normally active
individual, a balanced diet without supplements should meet
their needs. Even in extreme endurance activities such as the Tour De France,
estimated protein needs of 1.5 gms protein/kg body wt/day were easily met by
a normal (or "unsupplemented") diet that met total daily Caloric needs.

A literature review failed to support the use of protein supplements on
a balanced daily diet (a normal distribution of protein/carbohydrates/fats). In fact
it was suggested a potential for a DECREASE in overall performance
from the appetite suppressing effects of a high protein diet which in turn led to a decrease
in carbohydrate intake (and pre event muscle glycogen stores).

Can you eat too much protein? One study with protein intakes of over 2.5 grams
per kg of body-weight along with showing no additional benefit
above the 1.6 grams of protein/kg/day need (as determined by nitrogen balance
studies) also suggested an increased risk of
urea (a byproduct of protein metabolism) overload and dehydration at
these supra-maximal levels. Longer term
studies of large groups show a high protein/low carbohydrate diet
increases the risk of kidney stones and bone loss. In a study from the
University of Texas of 10 volunteers on a high protein/low carbohydrate diet for two weeks
blood uric acid levels (uric acid is a major cause of kidney stones) rose 90% and
urinary levels of citrate (which inhibits kidney stone formation) dropped 25%. A final
risk is the potential for weight gain as any extra protein Calories (beyond those
expend) are stored as fat, not muscle.

INCREASING PROTEIN NEEDS WITH AGING.

The US Recommended Dietary Allowance (RDA) for protein intake is 0.8 g/kg/day for adults. But
as we have just read, this may be on the low side for an athlete. How did that happen?
Most likely as the recommendation is based on nitrogen-balance studies in average young adults
who almost certainly have varying athletic leanings.

And it is probably too low for older adults
who are less efficient in their protein digestion and absorption. It has been speculated that
too little dietary protein and as a result being relatively relative protein deficient, may be an aggravating factor in the loss of muscle mass that accompanies aging.

Taking both aging and activity level into account,
an international panel of experts recommended protein intakes of 1.0 - 1.2 g/kg/day for all adults 65 years or older, with even higher intakes for those who are more physically active.

So for all of us who are riding regularly, and often competitively - even if just with friends
on the weekend, it is important to keep an eye on the protein content of our diets.

I have never been a fan of the over response with the paleo diets as the red meat comes along with a lot of undesirable fats. So if you want to err on the side of caution, there are plenty of
non meat sources of protein to add to your diet.

SOURCES OF PROTEIN

Lean beef, skinless chicken, and fish will provide about 7 grams of protein per ounce
(
quick online reference}.
Beans will provide 6 grams per 1/2 cooked cup, and rice (and other cereal grains) about
3 grams per 1/2 cup serving. A cup of milk or yogurt supplies 8 grams of protein. So it's
relatively easy to meet your basic protein requirements from 6-8 ounces of meat, 2-3
servings of dairy products, and 6-10 servings of cereal per day. And how about soy?
For
soy (tofu) it is 2.5 grams protein per ounce of tofu (10 grams protein
per half cup or 4 ounces tofu)

VEGETARIANS

A growing number of cyclists are moving toward meatless meals
or a completely meat free nutritional program. Not only are vegetarians healthier,
with lower rates of chronic diseases such as heart disease, obesity, and colon cancer,
but the fact that their diets are high in carbohydrates means they are constantly
"carob loaded".

Vegetarians as a group do not appear to be at excessive risk for protein deficiency
and in turn diminished athletic performance.But it is possible that in select individuals
with rigorously self-limited selections of
what they choose to eat, may be at some risk. The following is a specific example.

This is a summary from a presentation at the American College of
Sports Medicine 2018 Annual Meeting as reported in an article in Medscape online. It suggests that
vegetarians may be at performance risk from a lack of choline (an amino acid - a protein building block)
in their diet. (Eggs were the source of choline in this study.)

A few direct quotes from the article.

"Choline plays an essential role in cell membrane integrity, lipid transport,
and methylation. It is a precursor to acetylcholine, the neurotransmitter in motor
neurons that mediates muscle contraction."

"the study supplemented the diets of 37 people, 50 to 69 years of age, with different
amounts of choline. The 13 people assigned to the low group received 0.7 mg of choline per
kilogram of lean dietary mass, the 11 people assigned to the medium group received 2.8 mg/kg,
and the 13 people assigned to the high group received 7.5 mg/kg."

"Three times a week, the participants performed eight exercises in three sets of
eight to 12 repetitions at 70% of 1 maximum repetition."

"After 12 weeks of diet and exercise .... the researchers measured participant
strength as a composite of 1 maximum repetition bench press and 1 maximum leg extension.
On average, composite strength was lower in the low (choline) group than in the medium and
high groups (29.4% vs 46.8% vs 47.4%). The difference between the low and medium groups
was significant (P = .034)."

Their conclusion: "It is hard to get adequate amounts of choline from plant foods,
although it is present in, for example, soy beans."

A couple of my thoughts on this article:

The risk of low choline consumption would be highest in those avoiding animal fat and cholesterol
as part of a healthier diet.

Choline deficiency is an even higher risk for vegans, who are avoiding all animal products.

There was no difference between the middle and high supplementation groups so
"...more is not better". You just need a threshold amount.

They felt there was minimal potential for CV harm from the cholesterol in the eggs at the
supplement levels studied, so an easy way to supplement your diet might be to add a couple eggs a week
to your diet plan.

Finally, this was about development of muscle strength, not endurance. So it is
unclear how it might impact aerobic performance and endurance athletes.

There are a few tips to remember if you are considering a move to less meat.

Vegans, who eat no animal products whatsoever including dairy, need to be certain
they get enough

iron (from beans, kale, dried fruit, and collard greens). Don't use supplements
unless recommended by your physician because of the potential toxicity of too much
iron.

calcium (dark leafy vegetables, broccoli, citrus fruits)

choline

Eat "balanced" protein (because of the mix of amino acids, non meat protein
foods need to be eaten in combinations - same meal or in consecutive meals - to have the
right balance of amino acid building blocks to allow the body to use them to build and
repair tissue).

pinto beans and rice

grains (rice, bread, cereal) and legumes (peas or beans)

consider adding a couple eggs a week to assure you are getting enough choline

Eat a bit more than if you were eating meat as a protein source. For example a 3
ounce piece of meat contains about 21 grams of protein and is can be substituted with a
cup of cooked grain and a cup of cooked beans.

THE IMPACT OF GLUTEN RESTRICTION ON ATHLETIC PERFORMANCE.

A significant percentage of athletes eat a gluten (a grain protein) free diet - feeling it
helps performance. In this study
from Australia ~40% of the athlete group are on a gluten restricted diet.
This is
twice the rate of the general public ~20%.

The incidence of clinically proven gluten intolerance (celiac disease) with
documented inflammation of the small intestine is about 1% in the general population.
A critical review of gluten intolerance
suggested that non-celiac gluten sensitivity (NCGS - no inflammation of the bowel
on endoscopic biopsy) could be as frequent as 10%. Are athletes, who are
pushing their bodies to the max, more sensitive to even minimal symptoms of NCGS?
Is this another example of a placebo effect? Or athletes "just buying insurance",
eliminating any factor which might impact their performance. What is the data?

This study
looked at the short term (2 week) impact of a gluten free diet on cycling performance
or GI symptoms (which are common in elite athletes). A quote from the NYT
summarizes the findings. "Cycling performance had proven to be essentially
identical after a week in which a rider ate zero gluten or large amounts of gluten.
Inflammatory markers likewise were indistinguishable. For their part, the riders'
daily reports about the states of their digestive tracts and moods likewise
showed little variation whether a rider was eating gluten or not. Over all, Ms.
Lis said, 'we did not find a beneficial or negative effect of a gluten-free diet
for athletes who had no clinical necessity for the diet.' "

Points to be taken away?

This was a short term study. 2 weeks of gluten restriction. If you have true celiac disease,
this is too short a time for gastrointestinal tract inflammation to resolve completely.

This was a small study group. 13 participants. If 6 - 10% of the population have NCGS, it is likely only 1 of the study group might have suffered from that entity. And as the results are group results, a benefit might have been masked.

But the most important finding, I think, is that a gluten free diet did NOT impair
performance. So if you think you have NCGS, there is no clear downside to limiting your gluten intake.

There are two ways to express the daily intake of protein (P), carbohydrates (C), and fats (F).
One is as the absolute number of Calories derived from each dietary component. The other is
to express the balance of P/C/F as a relative ratio of the percent of total daily
Calories from each. As most diet analyses are expressed in relative terms, let's
use that to define a high protein diet.

What is the balance of protein/carbohydrates/fats in an "average" diet? For the average active individual,
not those participating in endurance sports, on a Calorically balanced diet, not trying to lose weight,
we find that Carbohydrates make up 45-65 percent of daily Calories, Fat 20-35 percent of Calories, and
Protein 10-35 percent.

The current controversy on healthy eating is over the appropriate balance of total Carbohydrates
versus total Fat in that average diet. There is solid evidence that IF you are not eating extra
carbohydrate Calories to support special athletic energy needs, you may be healthier if
you change that balance towards fewer carbohydrate Calories (neared lower range of 40 or 45 % of the daily total)
with more Calories from dietary fat (nearer 35 or 40%). In a Calorically balanced diet,
protein remains between 10 - 30%.

Dr. Sear's diet is based on a rigid Caloric ratio of 40% carbs, 30% protein and 30% fat along
with an emphasis on carbohydrates with a low glycemic index (providing a slow release of sugar
and minimal an insulin surge), lean protein, and fat that is monounsaturated.
It is similar to a Mediterranean Diet.

The term diet can be used in two ways. It can refer to

a low caloric, negative calorie balance eating program - a weight loss program

an approach to eating that emphasizes a preferred ratio of P/C/F Calories - a lifestyle eating program

The Zone diet can be used for both purposes. To lose weight you keep the correct ratio and focus on a negative
Caloric balance. If you are at your ideal weight, you eat a Calorically balanced diet and move the
focus to the P/C/F ratio.

Used to lose weight, evidence suggests that the Zone diet's emphasis on high protein and fat may have an
advantage over other weight loss programs, not the result of the original conjecture that it facilitated
fat metabolism as much as from a blunting of appetite which translated into the intake of fewer Calories
per day than the comparison diets.

After analyzing the dietary intake of the groups, the research team realized those on the
high protein diet had eaten less food. This accounted for the greater weight loss. There
were several possible explanations for this reduction in food intake. Protein has a higher
satiating (pronounced effect than carbohydrate. In other words, you feel less hungry when
consuming a diet high in protein. And a high protein intake seems able to suppress the
following days energy intake to a greater extent than carbohydrate.

For an athlete on any weight loss program, there is a significant
risk of riding in a metabolic state similar to that experienced with being "bonked" (when your glycogen is
depleted and no external glucose has being taken in). Dr. Sear's feels that it is this lack of glycogen
that forces the body to "burn" extra fat assisting with weight loss. Riding bonked is just part of
what one should expect - on the Zone or any other weight loss diet.

If you are not trying to lose weight, keeping the exact Zone ratio is alleged to provide the health benefit
from a decrease in total body inflammation and an increase in a sense of "well being". These
claims have yet to be proven in long term observations.

How about a Calorically neutral Zone diet and the athlete? Where Calories eaten
are adequate to replace those expended each day?

Although the Zone Diet claims to improve performance, a study on athletes following the diet lost
endurance. Why is that the case? The problem is in the rigid P/C/F ratio of 40/30/30.

If you want to maintain your weight (not gain weight) your daily Caloric expenditure and
intake have to be in balance.
Applying the Zone ratio to supply these Calories, an endurance athletes will not
eat enough carbohydrate Calories (at 30% of the total daily Calories eaten) to meet their higher level
exercise needs. With fat metabolism being less effective than carbohydrate metabolism to
support high level (>50 - 60% VO2max) activity, you bonk or run out of gas.

This is demonstrated in this study "The acute
1-week effects of the Zone diet on body composition, blood lipid levels, and performance in recreational
endurance athletes." Limiting daily carbohydrate Calories available (by sticking to the correct Zone ratio) led to slowly
progressive glycogen depletion.

The bottom line - To lose weight, using the Zone ratio with a negative daily caloric balance works. But on a calorically adequate daily diet it is unrealistic to expect that athletes will experience significant improvements in performance. The recommendations for both carbohydrate and Caloric intakes are not sufficient to meet the energy requirements of a regular daily training program. Go high protein/low carbohydrate and you'll be chronically bonked.

The paleo diet is the ultimate high protein approach to making diet choices.

It is based on the unproven assumption that our ancestors ate a high meat diet and
thus our metabolism is optimized for protein. But the data is not there to support
that assumption.

First we have the facts from many population studies that demonstrate a strong
correlation of health status with dietary intake - specifically the
negative impacts of a high meat diet versus the positive benefits of being a
vegetarian.

PROTEIN SUPPLEMENTS TO A NORMAL DIET

In his review of the literature
(original abstract) on dietary
protein supplements, Dr. Richard B Kreider PhD (Department of Human Movement Sciences &
Education, The University of Memphis, Memphis, Tennessee 38152.
Email: kreider.richard@coe.memphis.edu) concluded that "dietary supplementation of
protein beyond that necessary to maintain nitrogen balance does not provide additional
benefits for athletes."

Here is an excerpt of his review:

BACKGROUND. Protein and amino acids are among the most common nutritional supplements
taken by athletes. This review evaluates the rationale and potential effects on athletic
performance of protein, purported anabolic amino acids, branched-chain amino acids,
glutamine, creatine, and hydroxymethylbutyrate (HMB). LITERATURE. Two books, 61 research
articles, 10 published abstracts, and 19 review articles or book chapters. FINDINGS.
Dietary supplementation of protein beyond that necessary to maintain nitrogen balance does
not provide additional benefits for athletes. Ingesting carbohydrate with protein prior to
or following exercise may reduce catabolism, promote glycogen re-synthesis, or promote a
more anabolic hormonal environment. Whether employing these strategies during training
enhances performance is not yet clear. There is some evidence from clinical studies
that certain amino acids (e.g., arginine, histidine, lysine, methionine, ornithine, and
phenylalanine) have anabolic effects by stimulating the release of growth hormone, insulin,
and/or glucocorticoids, but there is little evidence that supplementation of these amino
acids enhances athletic performance. Branched-chain amino acids (leucine, isoleucine, and
valine) and glutamine may be involved in exercise-induced central fatigue and immune
suppression, but their ergogenic value as supplements
is equivocal at present. Most studies indicate that creatine supplementation may be
an effective and safe way to enhance performance in intermittent high-intensity exercise
and to enhance adaptations to training. Supplementation with hydroxymethylbutyrate appears
to reduce catabolism and increase gains in strength and fat-free mass in untrained
individuals initiating training; as yet, limited data are available to decide how it
affects training adaptations in athletes. CONCLUSIONS. Of the nutrients reviewed,
creatine appears to have the greatest ergogenic potential for athletes involved in
intense training. FURTHER RESEARCH. All supplements reviewed here need more evaluation
for safety and effects on athletic performance.

skimping on the carbohydrates needed for muscle glycogen repletion (risking the
development of chronic fatigue)

dehydration

potential kidney damage over time

and excessive bone loss (as protein increases urinary calcium loss).

What about protein in combination with carbohydrates in energy and post recovery drinks?
It had been suggested at one time that protein/cho mixtures were more effective than CHO
alone in repleted or supplementing muscle glycogen stores. The final word, in my mind,
is a review of 26 studies,
published in 2014. The conclusion: "When carbohydrate is delivered at optimal rates during
or after endurance exercise, protein supplements appear to have no direct endurance performance
enhancing effect. " And in addition, they expanded that conclusion to include supplements while
riding as well as in the post ride recovery period: "...when carbohydrate supplementation was
delivered at optimal rates during or after exercise, protein supplements provided no further
ergogenic effect, regardless of the performance metric used."

Theoretically, in intense exercise, protein post ride may help jump start the muscle repair process.
But this is theory and I am unaware of any studies that support this idea. The one reason
protein might be considered in a supplement or recovery drink in conjunction with CHO
would be to improve taste and in that way optimize supplement use (maximizing Calories replaced)
both during and after a ride. This could be especially important for those riders who do not tolerate
very sweet sugary drinks.

SOME PROTEIN IS "SAFER" THAN OTHERS - TMAO AND ATHEROSCLEROSIS

Cholesterol and saturated fats have been tagged as major risk factors for blood vessel disease
(atherosclerosis) for decades. But recent work suggests they are not the most important factor
in all those heart attacks. Merely a late stage contributor to damage already well under way.

The results of numerous studies and investigations points to Trimethylamine N-Oxide (TMAO)
as the real culprit.

There is proof of cause and effect. In an experimental mouse model, raising blood TMAO
levels by dietary manipulation increased blood vessel disease in the absence of any
changes in the cholesterol or fat content.

Numerous clinical studies of heart disease (chest pain in the ER, progression of known
atherosclerotic heart disease) show a direct correlation between increasing blood levels
of TMAO and cardiovascular disease.

Carnitine, a protein found in red meat and to a much lesser degree in chicken and fish, is the
source of TMAO. Any dietary carnitine not digested and absorbed in the small bowel passes into
the colon where bacteria (our microbiome) metabolize it to an intermediate molecule,
TMA. TMA is in then absorbed and modified further in the liver to TMAO.

There is a similar pathway for the production of TMAO from lecithin, a protein found in
egg yolks.

Solid evidence supports diet as the major determinant of blood TMAO levels. A
recent study documented that a diet low in red meat and eggs lowered TMAO levels
independent of the amount of cholesterol or saturated fats in those diets.

TMAO production can be reduced with oral antibiotics (which alter the makeup of the
microbiome) or by decreasing the dietary intake of carnitine. Vegans as a group have
the lowest blood TMAO levels (and the lowest rate of cardiovascular diseases) while
those on a regular red meat diet the highest. just replacing red meat with chicken
will lower the amount of TMAO excreted in the urine by two thirds.

What does this suggest for your diet?

Saturated fats, found in butter, cheese, red meat and other animal-based foods,
do play a role in the development of cardiovascular disease, but there risk
has been overstated.

Your decision on the source of the third component of the daily diet, protein, has
considerable impact on your health. We know that vegetarians have the lowest levels of
blood vessel disease, and your goal should be a move toward a meat free diet. But that
does not mean you have to move to a full vegetable protein oriented diet. You can cut
your risks by adding one or two meat free dinners a week.
Or decrease red meat portion sizes. And now we know that your choice of animal protein
should focus on substituting chicken or fish for red meat as much as possible.

THE BOTTOM LINE

Protein is necessary for the active athlete, but more is not necessarily better.
And for meat protein, chicken and fish are safer for your health than red meat.